Rise of invasive tiger shrimp reports expected as fall approaches

It was big enough for a meal, but the unusual catch was better off in the hands of researchers.

JANNETTE PIPPIN Daily News Staff

It was big enough for a meal, but the unusual catch was better off in the hands of researchers.

“That shrimp was definitely big enough for a shrimp dog, but we froze it instead,” said Mary Bryan Carlyle, who was with a group of friends who caught a jumbo Asian tiger shrimp this week in Carteret County waters.

Carlyle said they were in a canal at the mouth of the Broad Creek, out to catch some shrimp for a Labor Day dinner. When Jacob Clark pulled in his cast net, there was the one tiger shrimp and green tails, which they were after.

They had seen pictures of tiger shrimp and guessed this huge, black shrimp, which Carlyle estimated was 8 inches long, was one of them. They turned it over to Carlyle’s neighbor, who works at the N.C. Division of Marine Fisheries, so she could pass it on to biologists to confirm.

The report is the latest of only a handful so far this year. The three other reports have been from Hubert, Oak Island and Oriental.

Those few reports may not indicate tiger shrimp are scarce in Eastern North Carolina waters, however.

Dr. James Morris, a marine ecologist at NOAA’s Center for Coastal Fisheries and Habitat Research in Beaufort, said reports tend to drop as fishermen become more familiar with a species.

“People get used to them,” he said. “They’ve seen them before and don’t tend to report sightings.”

Morris, who conducts research on invasive species, said tiger shrimp are seen more in the fall and more reported sightings could appear. However, he said, they may need to look at new strategies for gauging the presence of the tiger shrimp, such as the use of monitoring programs by fisheries agencies.

But research to-date indicates tiger shrimp have a presence in North Carolina waters.

“It’s a little early this time of year for sightings, but we’re still seeing them and they are widespread,” Morris said.

Asian tiger shrimp are native to the western Indo Pacific, where they are a popular aquaculture species.

How they reached North Carolina is unclear. Some have escaped from an aquaculture facility. Others could have been swept on ocean currents from wild populations in the Caribbean or ship ballast waters.

About 300 tiger shrimp were collected off the coasts of South Carolina, Georgia and Florida in 1988 after the release from an aquaculture facility in South Carolina. But there are no longer any known tiger shrimp farms in the United States.

According to the National Oceanic and Atmospheric Administration, that was an isolated incident, and it wasn’t until 2008 that reports of the non-native shrimp arose.

Trish Murphey, a biologist with the Division of Marine Fisheries, has been recording reports of tiger shrimp in North Carolina since that time.

After receiving reports of 16 tiger shrimp being caught off the North Carolina coast in 2008 and 20 in 2009, that number spiked to 257 in 2011. Sam Meadow, a commercial fisherman from Cedar Point, contributed to the 2011 numbers after catching 32 tiger shrimp in the Cape Fear area and bringing them back to Carteret County to show.

The 2011 reports followed Hurricane Irene, which passed through in August and may have been a contributing factor.

While the reports have dropped back down, Murphey and Morris say the tiger shrimp are out there in numbers beyond what may be observed — and there is good reason to watch their presence.

“The fact that they are here is a concern,” Murphey said.

As an invasive species, there are concerns about impacts on the native shrimp, displacing them from their natural habitat. There can also be transmissions of disease.

What impacts tiger shrimp may have on North Carolina’s native shrimp is not yet known but has the attention of researchers.

Species such as the non-native lionfish have reached invasion status in North Carolina. If tiger shrimp keep growing in numbers, they could follow suit.

“That’s part of it; trying to figure out where tiger shrimp are in that invasion timeline,” Morris said.

While out on Queen Creek in July, Bobby Riggs and Naomi Roberts of Hubert found two unusual looking shrimp in their catch.

“We’ve been shrimping for a lot of years and we knew right away what they were,” said Roberts.

Roberts and her husband, a commercial fisherman, knew about the presence of the tiger shrimp in North Carolina waters and recognized the distinctive black-gray color.

They hadn’t yet reached the large size that tiger shrimp are known for but were definitely not North Carolina shrimp.

“One looked like a mix of a bunch of different shrimp,” Roberts said.

They contacted the Division of Marine Fisheries as well, aware that fisheries officials had asked fishermen to report any tiger shrimp they catch.

Roberts said it didn’t take much for them to haul in two, and she suspects there are plenty of other tiger shrimp out there.

“We had two in only a small bucket,” she said.

DMF Biologist Murphey said tiger shrimp are not currently a species they monitor through the division’s formal sampling program, but biologists report them if they catch any.

And the tiger shrimp have been caught from Albemarle and Core Sounds south to Cape Fear.

“They are pretty much throughout our North Carolina (coastal) waters,” Murphey said.